let obj={
    'jia' : function(a,b){
        console.log(a+b);
    },
     'jian': function (a,b){
        console.log(a-b);
    },
    'cheng' : function (a,b){
        console.log(a*b);
    },
    'chu' : function (a,b){
        console.log(a/b);
    },

    'new':function(a,b){
        this.jia(a,b);
        this.jian(a,b);
        this.cheng(a,b);
        this.chu(a,b);
    }
    };
    module.exports=obj;